1. Field of the Invention
The present invention relates to a nursing bed capable of allowing a nurse or attendant to change the bedding such as a mat or futon for a patient, to raise the back of the body of the patient and to change the lying posture of the patient on the bed plate, and also capable of adjusting the height thereof, the height of the lower and upper portions of the patient's body, lifting the patient in a hammock fashion and allowing the patient to use a chair on the bed plate.
2. Description of the Related Art
As prior art technology, there exists an invention entitled "A Medical Treatment Bed" disclosed in Japanese Patent Application No. 140650/1994 which was filed by the present applicant on May 20, 1994. According to paragraph 1 of the scope of claim for patent column of the specification attached to the application, there is a description reading "A medical treatment bed comprising a base (1), two movable portions (3) respectively arranged at leg-side and head-side ends of the base (1) and capable of being adjusted of their heights by means of cylinders (2) or motors, an independent bed plate (6) placed on the central portion of the base (1) so as to allow bedding (4) such as a mat or futon to be placed thereon and provided with fixing holes (5) at both sides of the leg-side end and the head-side end of the base (1), a pair of leg-side arms (7) separated from each other by a distance longer than the width of the bed plate (6) and projecting toward the head-side end of the bed plate (6) from the leg-side movable portions (3), respectively, a flexible and gas-permeable mesh-like or cloth-like lower leg support member (8) removably stretched over the whole of the pair of leg-side arms (7) or over a desired region excluding the waist portion of a patient, a pair of head-side arms (9) separated from each other by a distance longer than the width of the bed plate (6) and projecting toward the leg-side end of the bed plate (6) from the head-side movable portions (3), respectively, a pair of backrest arms (1) respectively arranged at the head-side arms (9) and capable of being adjusted of their angles by cylinders (2) or motors, a flexible and gas-permeable mesh-like or cloth-like upper body support member (11) removably stretched over the whole of the pair of the backrest arms (10) or over a desired region excluding the waist portion of the patient, and fixing means (12) such as knockpins respectively arranged at the leg-side arms (7) and at the head-side arms (9) and capable of fixing and releasing the bed (6) through the fixing holes (5) and characterized in that when the bed (6) is fixed between the pair of leg-side arms (7) and between the pair of headside arms (9) by means of the fixing means (12), the lower leg support member (8) and the upper body support member (11) cover the upper surface of the bedding (4)."
However, the above-described "medical treatment bed" has had the following five problems.
(1) When a patient is lifted in a hammock fashion, since a space which is wide enough to receive the waist of the patient is provided between the "lower leg support member" and the "upper body support member", the waist of the patient sometimes slips down from the space so that the patient not only has to assume a disagreeable posture, but there is also a fear of his falling down onto the bed plate. Because of such structure, it is not possible to keep him under a hammocked condition.
(2) When the back of the patient is raised, since the angle of the "backrest arms" is adjusted about a fixed shaft, when the angle of inclination of the "upper body support member" becomes large, the upper portion of the patient's body (especially the back and waist of the body) is strongly pushed forward so that the whole of the patient's body slips forward. On the contrary, where the back of the patient's body is lowered by reducing the angle of the "backrest arms", the "upper body support member" moves away from the patient's body while leaving the body at the moved position so that the patient comes to lie on his back on the bed plate. Therefore, if the patient can not move himself because of his health condition, he will not be able to return to his original lying position, so that his attendant will have to move his body toward the head-side end of the bed plate.
(3) Even when it is desired to shift the backrest position of the patient forward or rearward depending on his physical form or his health condition, since the positional relationships among the "head-side arms", the "backrest arms" and the "upper body support member" are not flexible, it is not possible to adjust the position at which the back of the patient's body is raised.
(4) Even when the extended conditions of the "lower-leg support member" and the "upper body support member" are desired to be changed when lifting the patient's body in a hammock fashion or the back of the patient is raised, since the "lower-leg support member" and the "upper body support member" are directly and removably fixed to the "leg-side arms" and the "patient's back raising arms", respectively, it is not possible to strongly stretch or loosen the members. When extension conditions of both of the members are changed, there is no other choice than adjusting the length of each of them in advance when fixing them.
(5) Where the position of the body of the patient is changed from its usual supine position to its recumbent position, quite the same operation as the usual operation is required, so that his attendant must make a great effort to do so, at the risk of damaging his own body.